The former All Blacks centre - who will spend time playing in Japan before returning to the NRL next season - believes that Cooper has the skills to make the transition to the 13-man-code.

Cooper has been under pressure of late, particularly following the Wallabies' 22-0 Rugby Championship loss to New Zealand two weeks ago, and has flirted with crossing codes in the past.

"If people are saying he is not wanted in rugby - first off, I think they are crazy and don't know what they're talking about - but if they think he is not good enough to be playing for Australia then I would love to lure him across to rugby league for a year," Williams told the Sunday Telegraph.

"I will try. I would definitely love to play alongside him. I think he would be a success. I have spoken to him about it. He would be great to run off."

Williams - who has been linked with the Sydney Roosters - is confident that Cooper could cause damage in league given the extra space afforded to attackers.

"His skill-set is definitely right up there, right at the top, what he brings to the table in terms of running, off-loads, kicking, is incredible," Williams said. "I reckon he would be a huge success, he has definitely got the skill-set to play the 13-man game.

"The biggest difference is that in rugby you are playing on the advantage line, whereas in league the defence is 10 metres back. Imagine what he could do with that extra space. And I think it is easier to make the transition from union to league, rather than going from league to union."